Tesla Hit it Out of the Park!

The Tesla Model S sedan, which should be delivered to the first customers in about a month, will be available with three different sizes of battery packs (40kWh, 60kWh and 85kWh). Tesla's goal with the top of the line model was to achieve a 300 miles driving range using the EPA 2-cycle test, the same one that gave the Tesla Roadster its official 244 miles range. It was an ambitious goal, considering that the Model S is bigger than the Roadster and less expensive, so there's less money to spend on the battery (thankfully, battery technology keeps improving and getting a bit cheaper every year).

Well, it looks like Tesla hit it out of the park. Since the Roadster was released, the EPA has changed its testing cycle a bit (more on that below), but if we compare Apples to Apples, the Model S has 320 miles of driving range. That's significantly more than any other production electric car!

New EPA Rating Procedures: 5-cycle vs. 2-cycle

When the Tesla Roadster was certified, the EPA only used a 2-cycle test that was carried out under conditions of 75 degrees Fahrenheit ambient temperature and with varying acceleration rates and driving speeds for both city and highway tests topping out at 60 mph. Recently, the EPA incorporated three additional cycles into their tests that push vehicles to greater limits. The additional cycles added as part of the new “5-cycle test” include a cold driving cycle that requires heater use, a hot weather cycle with air conditioning operation, and a high-speed cycle (reaching 80mph) with rapid accelerations.

We are very pleased to report that Model S has exceeded our initial range expectations by about 20 miles and has achieved a Roadster equivalent 2-cycle range of 320 miles and a 5-cycle range of 265 miles. This sets a new record for electric vehicle range! (source)

Of course, the actual real-world range of any electric car depends heavily on how you drive it, same as with a gasoline car. If you drive it at ideal speeds and don't use air conditioning or the heater too much, you could get more than the EPA's number (many Roadster or LEAF drivers have testified to that), while if you drive at very high speed with lots of A/C or heating, you could get significantly less range.

How does the Model S do it? A good part of it is extremely good aerodynamics:

Even though the Model S is a much larger and heavier car than Roadster with ridiculously more cargo capacity the total battery energy consumption on the highway is only about 10% more than for the Roadster! This is quite amazing and results largely from the Model S having the best aerodynamics of any sedan in its class with a Cd of approximately 0.24. Model S aerodynamics are so optimized that the total aerodynamic drag force experienced by the car – which is significantly larger in frontal area – is almost the same as a Roadster for a given speed.